NoSQL databases: data consistency, nosql Database Consistency

Source: Internet
Author: User

NoSQL databases: data consistency, nosql Database Consistency
NoSQL Database: Data Consistency
Read consistency

  • High Consistency
    Access any node in the cluster at any time, and the data obtained is consistent;

  • User consistency is consistent with the data obtained during cluster access for the same user;
    Solve user consistency: Use a sticky session to bind the session to a specific node for processing;
    This will reduce the performance of the Load balancer;

  • Final consistency
    Temporary data inconsistency occurs between nodes in the cluster due to delayed data synchronization. However, after data synchronization is completed, the data consistency is achieved;

Update consistency
  • Pessimistic Mode
    The use of write locks significantly reduces system response capabilities and may lead to deadlocks.
  • Optimistic
    Conflict occurs first, and then the processing method of automatic merging of sequence is extremely "domain-specific ".
Relax "consistency constraints"
  • CAP Theorem
    Consistency, Availability, and Partition tolerance. The three attributes can only satisfy two at the same time;

Partition tolerance explanation: the cluster is still available when it is divided into multiple due to communication faults

  • CA system
    "Partition" is not available in a single server cluster
  • PA/PC
    When a "partition" occurs in a cluster, the trade-off between "consistency" and "availability" generally sacrifices partial consistency (eg: Use final consistency) to ensure availability.
Relax "persistence" constraints

More Strict Persistence means more performance loss;

  • Sacrifice "durability" in exchange for better performance
  • Replication "persistent" Fault
    Master node failure, not synchronized to data loss from the slave node master node recovery, data conflict solution updated during the fault: specify the required durability for a single request
Mind Map

Reference

NoSQL Essence

Posted by: Large CC | 30JUN, 2014
Blog: blog.me115.com [subscription]
Weibo: Sina Weibo

Copyright Disclaimer: This article is an original article by the blogger and cannot be reproduced without the permission of the blogger.

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